Klystron control circuit

ABSTRACT

Disclosed is a klystron modulator and mode control circuit. The output at the plate of a conventional pentode electron-coupled oscillator is used to drive a voltage doubler connected to produce a negative output voltage, a portion of the output of the voltage doubler being fed back to the ungrounded suppressor grid of the pentode to provide regulation. By applying the oscillations of the electron-coupled oscillator and the negative output voltage of the voltage doubler to the repeller lead of a klystron, it is possible to provide, in a single tube, both the a-c voltage desired for repeller modulation of the klystron and the negative d-c voltage needed to bias the repeller. By detecting the amplitude modulation on the output of the klystron and phase-comparing the detected voltage with the modulating voltage, a correction voltage is produced which can be inserted in the voltage doubler circuit such that the negative bias remains at a value which will maintain the klystron on mode center.

5 a; nite States atent 1191 1 1 3,882,423 Gerwin et al. May 6, 1975 KLYSTRON CONTROL CIRCUIT [57] ABSTRACT [75] Inventors: Harry L. Gerwin, Bethesda, Md.; Disclosed is a klystron modulator and mode control Robert J. Darcey; Houston D. Hoyt, circuit. The output at the plate of a conventional penboth of Alexandria, Va. tode electron-coupled oscillator is used to drive a volt- [73] Assignee, The United States of America as age doubler connected to produce a negative output voltage, a portion of the output of the voltage doubler represented by the Secretary of the Arm Washin ton D C be1ng fed back to the ungrounded suppressor grid of g the pentode to provide regulation. By applying the os- [22] Filed: July 12, 1957 cillations of the electron-coupled oscillator and the negative output voltage of the voltage doubler to the [21] Appl' 671572 repeller lead of a klystron, it is possible to provide, in a single tube, both the a-c voltage desired for repeller [52] US. Cl 332/7; 332/58 modulation of the klystron and the negative d-c volt- [51] Int. Cl. H015 1/02 age needed to bias the repeller. By detecting the am- [58] Field of Search 332/7 plitude modulation on the output of the klystron and phase-comparing the detected voltage with the modu- [56] References Cited lating voltage, a correction voltage is produced which UNITED STATES PATENTS. can be inserted in the voltage doubler circuit such that 2,343,539 3/1944 Edson 331/176 negative bias remains at a value which Wm main 2,451,021 10/1948 Detuno 331/75 the klystron mode center- 2,58l,404 1/1952 Ginzton 332/7 2,695,358 11/1954 Bush 325/40 Primary Examiner-Maynard R. Wilbur Assistant ExaminerN. Moskowitz Attorney, Agent, or Firm-Nathan Edelberg; Robert P. Gibson; Saul Elbaum 2 Claims, 1 Drawing Figure MODULZTION PATENTED HAY 6 ms 7/ AM. DETECTOR COMPARATOR 7 .9/ a 30 25 90 LQ52J REF 1 MODULATION INVENTOR; Harry L. Gerwin Robert J. Darcey BY Houston D. Hoyt KLYSTRON CONTROL CIRCUIT The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to us of any royalties thereon.

This invention relates to a klystron modulator and mode control circuit. The invention provides a circuit which will repeller-modulate a klystron, supply the negative d-c voltage for the repeller of the klystron, and maintain the klystron on mode center so that the klystron will operate at maximum power output. The prior art has not been able to provide a circuit with these features.

In a typical embodiment of the invention, the output at the plate of a conventional pentode electron-coupled oscillator is used to drive a voltage doubler connected to produce a negative output voltage, a portion of the output of the voltage doubler being fed back to the ungrounded suppressor grid of the pentode to provide regulation. By applying the oscillations of the electroncoupled oscillator and the negative output voltage of the voltage doubler to the repeller lead of a klystron, it is possible to provide, in a single tube, both the a-c voltage desired for repeller modulation of the klystron and the negative d-c voltage needed to bias the repeller. By detecting the amplitude modulation on the output of the klystron and phase-comparing the detected voltage with the modulating voltage, a correction voltage is produced which can be inserted in the voltage doubler circuit such that the negative bias remains at a value which will maintain the klystron on mode center.

One object of this invention is to provide an improved regulated power supply.

Another object is to provide a single tube modulator and adjustable regulated bias supply for the repeller of a klystron.

A further object is to provide a circuit which will repeller-modulate a klystron, supply the negative d-e voltage for the repeller of the klystron, and maintain the klystron on mode center so that the klystron will operate at maximum power output.

The specific nature of the invention, as well as other objects, uses, and advantages thereof, will clearly appear from the following description and from the accompanying drawing, in which:

The drawing shows a schematic diagram of a klystron modulator and control circuit in accordance with the invention.

In the drawing, a pentode 15 is used a a Hartley-type electron-coupled oscillator by having its screen grid 18 connected to one end of a tuned circuit 25 comprising an inductor 26 and a capacitor 27, and its control grid 19 connected to the other end of the tuned circuit 25 through a d-c blocking capacitor 85, the cathode 14 of the pentode being grounded. The cathode 14, control grid 19 and screen grid 18 operate as a Hartley oscillator, B+ voltage being supplied to the screen grid 18 by connecting the B+ voltage to the appropriate tap on the inductor 26, the capacitor 85 and the potentiometer resistance 75 serving as the grid-leak network for the oscillator.

The output of the electron-coupled oscillator is used to drive a voltage doubler. The primary winding 31 of a transformer 30 is connected in the plate lead of the pentode 15, the secondary winding 32 of the transformer 30 having a capacitor 33 connected across it, the capacitor 33 having a value which provides maximum output from the oscillator. Connected to the secondary winding 32 is a two-diode, two-capacitor voltage doubler circuit, the plate of diode 22 and the cathode of diode 23 being connected to one end of the secondary winding 32, and the junction of the two capacitors 42 and 43 being connected to the other end of the secondary winding 32. A resistor 60 is connected in series with the diode 22, and the secondary winding 92 of a correction voltage transformer is connected in series with the diode 23, the junction of the resistor 60 and the capacitor 43 being connected to circuit ground. Feedback voltage is supplied to the suppressor grid 17 of the pentode 15 by means of a potentiometer 105 having its ends connected between the junction of capacitors 42 and 43 and a reference voltage E the variable arm of the potentiometer 105 being connected to the suppressor grid 17. A capacitor 81 is connected between the suppressor grid 17 and circuit ground to place the suppressor grid 17 at effective a-c ground at the oscillation frequency of the oscillator.

The negative output voltage B- of the voltage doubler is applied to the repeller 71 of a klystron 70 through an r-f isolating choke 94. The klystron 70 is modulated by applying part of the oscillation voltage from the electron-coupled oscillator to the repeller 71 by means of the potentiometer 75, the capacitor 101 providing d-c blocking. To obtain mode control of the klystron 70, the output of the klystron 70 is fed to an amplitude modulation detector and phase comparator circuit which detects the amplitude modulation on the output of the klystron 70 and phase-compares the detected voltage with the modulating voltage, producing a correction voltage which is then applied to the primary winding 91 of the correction voltage transformer 90. Skilled persons will be able to design the amplitude modulation detector and phase comparator 95 so that the correction voltage will have an amplitude proportional to the amount the negative bias on the repeller 71 is off mode center, and have a phase relation relative to the modulating voltage so that the voltage appearing at the secondary winding 92 of the transformer 91 will be such that the negative bias B- will be changed in the amount necessary to place the klystron 70 on a mode center.

A unique feature of the circuit shown in the drawing is that the repeller negative bias source B can be adjusted to provide any desired source impedance by adjusting the value of the resistor 60 in series with the diode 22. In fact, either the do or a-c output impedance may be reduced to zero by proper choice of this resistor 50.

Other unique features of the circuit include the manner in which regulation is obtained and the manner in which the correction voltage is applied to the voltage doubler circuit. By feeding back the voltage at the junction of the capacitors 42 and 43 to the suppressor grid 17, the voltage obtained at the junction point is stabilized, this voltage being the output of the first half-wave rectifier made up of the diode 22 and the capacitor 43. The resistor 60 magnifies the effect of a change in out put from this first half-wave rectifier. The correction voltage appearing at the secondary winding 92 is injected in series with the second diode 23, the correction voltage adding or subtracting from the voltage supplied by the secondary winding 32 of the transformer 30. Consequently the voltage output of the second halfwave rectifier made up of the diode 23 and the capacitor 42 can be changed by an amount determined by the correction voltage. Since the negative bias voltage B applied to the repeller 71 of the klystron 70 is the sum of the output voltages from the first and second halfwave rectifiers, the negative bias B- is not only stabilized, but can also be changed in amount in response to a correction voltage to maintain the klystron 70 on mode center.

It will be apparent that the embodiment shown is only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

We claim:

1. A klystron modulator and mode control circuit, comprising in combination: an electron-coupled oscillator having a pentode with an ungrounded suppressor grid; a transformer having its primary winding connected in the plate circuit of said pentode tube; a voltage doubler comprising first and second diodes and first and second capacitors, the plate of said first diode and the cathode of said second diode being connected to one end of the secondary winding of said transformer, one end of said first capacitor being connected to the cathode of said first diode, said cathode of said first diode being at circuit ground, and one end of said second capacitor being connected to the plate of said second diode, the other ends of said first and second capacitors being connected to the other end of said secondary winding; a potentiometer having its ends connected between a reference voltage and the junction of said first and second capacitors and its variable arm connected to the suppressor grid of said pentode tube, movement of the variable arm of said potentiometer varying the voltage applied to said suppressor grid causing the negative output voltage of said voltage doubler obtained between the plate of said second diode and circuit ground to be varied; means for applying a portion of said electron-coupled oscillator voltage to the repeller of a klystron to cause modulation of said klystron; means for applying said negative output voltage of said voltage doubler to said repeller to provide a negative bias for said repeller; and means for controlling said negative bias on said repeller to maintain said klystron on mode center, said means for controlling including means for injecting a correction voltage in series with said second diode, said correction voltage having an amplitude proportional to the amount said repeller bias is off mode center and having a phase relative to said klystron modulating voltage such that said output voltage of said voltage doubler changes in the amount necessary to place said klystron on mode center.

2. A klystron modulator and mode control circuit, comprising in combination: an electron-coupled oscillator having a pentode with an ungrounded suppressor grid; a transformer having its primary winding connected in the plate circuit of said pentode tube; a voltage doubler comprising first and second diodes and first and second capacitors, the plate of said first diode and the cathode of said second diode being connected to one end of the secondary winding of said transformer, one end of said first capacitor being connected to the cathode of said first diode, said cathode of said first diode being at circuit ground, and one end of said second capacitor being connected to the plate of said second diode, the other ends of said first and second capacitors being connected to the other end of said secondary winding; a potentiometer having its ends connected between a reference voltage and the junction of said first and second capacitors and its variable arm connected to the suppressor grid of said pentode tube, movement of the variable arm of said potentiometer varying the voltage applied to said suppressor grid causing the negative output voltage of said voltage doubler obtained between the plate of said second diode and circuit ground to be varied; means for applying a portion of said electron-coupled oscillator voltage to the repeller of a klystron to cause modulation of said klystron; means for applying said negative output voltage of said voltage doubler to said repeller to provide a negative bias for said repeller; and means for controlling said negative bias on said repeller to maintain said klystron on mode center, said means for controlling including a correction voltage transformer having its secondary winding connected in series with said second diode, and means for detecting the amplitude modulation on the output of said klystron and phase comparing said detected voltage with said modulating voltage to produce a correction voltage which is applied to the primary winding of said correction voltage transformer, said correction voltage having an amplitude proportional to the amount said repeller bias is off mode center and having a phase relative to said klystron modulating voltage such that said output voltage of said voltage doubler changes in the amount necessary to place said klystron on mode center. 

1. A klystron modulator and mode control circuit, comprising in combination: an electron-coupled oscillator having a pentode with an ungrounded suppressor grid; a transformer having its primary winding connected in the plate circuit of said pentode tube; a voltage doubler comprising first and second diodes and first and second capacitors, the plate of said first diode and the cathode of said second diode being connected to one end of the secondary winding of said transformer, one end of said first capacitor being connected to the cathode of said first diode, said cathode of said first diode being at circuit ground, and one end of said second capacitor being connected to the plate of said second diode, the other ends of said first and second capacitors being connected to the other end of said secondary winding; a potentiometer having its ends connected between a reference voltage and the junction of said first and second capacitors and its variable arm connected to the suppressor grid of said pentode tube, movement of the variable arm of said potentiometer varying the voltage applied to said suppressor grid causing the negative output voltage of said voltage doubler obtained between the plate of said second diode and circuit ground to be varied; means for applying a portion of said electron-coupled oscillator voltage to the repeller of a klystron to cause modulation of said klystron; means for applying said negative output voltage of said voltage doubler to said repeller to provide a negative bias for said repeller; and means for controlling said negative bias on said repeller to maintain said klystron on mode center, said means for controlling including means for injecting a correction voltage in series with said second diode, said correction voltage having an amplitude proportional to the amount said repeller bias is off mode center and having a phase relative to said klystron modulating voltage such that said output voltage of said voltage doubler changes in the amount necessary to place said klystron on mode center.
 2. A klystron modulator and mode control circuit, comprising in combination: an electron-coupled oscillator having a pentode with an ungrounded suppressor grid; a transformer having its primary winding connected in the plate circuit of said pentode tube; a voltage doubler comprising first and second diodes and first and second capacitors, the plate of said first diode and the cathode of said second diode being connected to one end of the secondary winding of said transformer, one end of said first capacitor being connected to the cathode of said first diode, said cathode of said first diode being at circuit ground, and one end of said second capacitor being connected to the plate of said second diode, the other ends of said first and second capacitors being connected to the other end of said secondary Winding; a potentiometer having its ends connected between a reference voltage and the junction of said first and second capacitors and its variable arm connected to the suppressor grid of said pentode tube, movement of the variable arm of said potentiometer varying the voltage applied to said suppressor grid causing the negative output voltage of said voltage doubler obtained between the plate of said second diode and circuit ground to be varied; means for applying a portion of said electron-coupled oscillator voltage to the repeller of a klystron to cause modulation of said klystron; means for applying said negative output voltage of said voltage doubler to said repeller to provide a negative bias for said repeller; and means for controlling said negative bias on said repeller to maintain said klystron on mode center, said means for controlling including a correction voltage transformer having its secondary winding connected in series with said second diode, and means for detecting the amplitude modulation on the output of said klystron and phase comparing said detected voltage with said modulating voltage to produce a correction voltage which is applied to the primary winding of said correction voltage transformer, said correction voltage having an amplitude proportional to the amount said repeller bias is off mode center and having a phase relative to said klystron modulating voltage such that said output voltage of said voltage doubler changes in the amount necessary to place said klystron on mode center. 